In real world, we would call protocol each country language. For Greeks, the protocol is Greek. With this protocol, the Greeks can communicate together because they have the same protcol. But they cannot communicate with Africans as they have not the same protocol.

In computer for example, there are several protocols. One of them is the HTTP (hyper text transfer protocol). This is the way that the client and the serever must both know in order to communicate together!

For communicate two PICs together for example, you need to make a protocol or use a ready one to make them understand together. For example, how can a PIC tell to another PIC "Turn on output 1"? The answer that someone will give a very small protocol!

protocols are much needed not only in communications, but also in electronics, electrical etc.

protocols are made to establish standards for devices so that it can easily adopt hardware or software changes now and in the future. it is made so that devices communicate and understand with each other.